Kentucky Sen. Rand Paul accused Dr. Anthony Fauci of covering up and downplaying the possibility that the COVID-19 pandemic was the result of a lab leak. After a former top government scientist in China said not to rule out any possible origin theory, Paul vowed on "America's Newsroom" Wednesday to uncover the truth.

SEN. RAND PAUL: From day one, from January 31 of 2020, [Fauci] was conspiring with fellow virologists to cover this up because he knew he had been one of the world's leading advocates of gain of function research for at least a decade. He's quoted as saying that gain of function research is so important that even if a pandemic breaks out, it'll be worth the knowledge. He'd been an advocate for a decade. He was an advocate and the chief architect of funding the lab in Wuhan. So he knew from the very beginning if this leak from the lab in Wuhan, that the guilt, the culpability for the pandemic would attach to his horrific decision to fund this lab. And so, no, he's been trying to cover it up from day one. It's only in the last six months or so he started saying this "open mind" thing. But no, he's been part of an elaborate cover-up to make sure that no one ever knew the truth. But we're going to get to the truth, I promise.

SEN. RAND PAUL TAKES AIM AT DR. FAUCI IN NEW BOOK FOCUSED ON THE COVID-19 'COVER-UP'

Sen. Rand Paul, R-Ky., and Dr. Anthony Fauci, White House chief medical adviser and director of the NIAID

Sen. Rand Paul, R-Ky., clashed with Dr. Anthony Fauci, White House chief medical adviser and director of the NIAID, during a Senate Health, Education, Labor, and Pensions Committee hearing to examine the federal response to COVID-19 and new emerging variants on Jan. 11, 2022 at Capitol Hill in Washington. (Photo by GREG NASH/POOL/AFP via Getty Images) (GREG NASH/POOL/AFP via Getty Images)

Sen. Rand Paul will release a book later this year that focuses on the origins of the coronavirus pandemic, and argues that former National Institute of Allergy and Infectious Diseases' director Dr. Anthony Fauci deceived the world about the disease.

The book is called "Deception: The Great Covid Coverup" and will be released in October by Regnery Publishing, a Salem Media Group company and the publisher of numerous conservative books.

"Covid-19 was deadly, but the real killer was the cover-up, led by Anthony Fauci — America’s most durable medical bureaucrat — who knew from the beginning the virus was likely genetically engineered and possibly leaked from a lab," Paul said in a statement in the publisher's news release. "He knew because he’d skirted regulations and funded gain-of-function research in Wuhan and elsewhere. We can’t allow Fauci and his yes-men to walk away from what they’ve done, or the next pandemic may be far worse."

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Paul has consistently taken aim at Fauci for his role in the COVID-19 pandemic response, and has criticized the health official for the NIAID's involvement with the Wuhan, China, lab that studied coronaviruses.

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Fox News' Kyle Morris contributed to this report.